How Satellite Phones Work

It seems like not that long ago when you wanted to use the phone, your
were relegated to your home, office, or other place where there was a
landline. No longer. With the advent of cell phones, people
have learned they can communicate anytime, anywhere. Unless, of
course, they are in a spot where there isn't a cell phone tower.
What then? When it comes to the most comprehensive global coverage,
consider the satellite phone.

Satellite phones are more expensive to buy and operate than cellular
phones. They are considerably more bulky and don't work indoors
without an external antenna. But if you are frequently in areas
where cellular phone service isn't available, a satellite phone is a
terrific option for staying mobile and in touch.

How do satellite phones work? Just like cellular phones, satellite
phones use radio waves to send their signal. Because satellite
phones use satellite signals, the antenna is a little larger, and they
must be used in an area where there is unobstructed sky.
Surprisingly, satellite phone services have been available for more than
25 years. There are several different types of satellite phone
services, but the most important difference is whether the service uses
low earth orbit (LEO) satellites or geosynchronous — sometimes
called geostationary — satellites.

LEO Satellites

LEO satellites, which are in lower orbit, move relative to the earth's
surface. Heights of LEO satellites vary greatly. LEO orbits
can be polar, which means that they circle around each pole.
Satellites that do not orbit each pole don't reach the Arctic and
Antarctic regions, which are the highest and lowest reaches of the
earth. The lower orbit a satellite has, the less coverage it
has. So you need more LEO satellites in order to provide global
coverage. Satellite phones that use LEO satellites have an
unnoticeable delay, and the phones are more portable because they don't
need to send or receive a signal from a very great distance.

Geosynchronous Satellites

These satellites, which are at a fixed height of 22,300 miles above the
earth, rotate around the earth at the same speed as the earth.
Because of this, the satellite appears to be stationary. One
satellite can cover about a third of the earth's surface. However,
some of them have directional antennas that limit the service areas.
Because the signal has to be sent so far, satellite phones that use
geosynchronous satellites have fairly noticeable response delays.